Photosensitive compositions, e.g., hexaarylbiimidazole/leuco compositions have been found to be of use in photographic applications because of their ability to form permanent colored images rapidly upon exposure to electromagnetic-irradiation, particularly in the ultraviolet region. However, since they are also sensitive to visible light and form color upon exposure to such light, it is difficult to prevent color formation in such compositions upon exposure to ambient room light, sunlight, or daylight, and thus it is difficult to handle the compositions.
In order to retain an image once it has been formed, color development in the unilluminated portions of the image pattern by exposure to ultraviolet radiation must be avoided. It is known to preserve the original image by applying to the imaged material, e.g., by spraying or immersion, a solution of hydroquinone. While this is advantageous in preserving or fixing the original image, more effective agents are desirable, i.e., those which have a rapid deactivation effect coupled with excellent ambient light stability.
It is also desirous that leuco dye/photooxidant compositions coated on suitable supports possess sufficient dark stability to permit coatings to be useful for extended periods of time, that the coated products can be handled for limited periods of time in ambient light environments without change, both prior to, and subsequent to the imaging exposure, that they have good dot rendition, and that the coated products can be made permanently stable when this is desirable.